Impact-operated electricity generator for projectiles

ABSTRACT

An electrical current generator for projectiles which is operated by impact. A cap is mounted so as to transfer direct forces to a striker which in turn compresses a substance which responds by generating current. To accommodate indirect or angular forces, the cap is mounted for translatory displacement which by a camlike action is converted into axial displacement of the striker to compress said substance.

Unite States atent Inventor Francis Albert Daniel Andre Bourges, France App]. No. 886,201 Filed Dec. 18, 1969 Patented June 15, 1971 Assignee ETAT Francais Paris, France Priority Dec. 19, 1968 France 179,258

IMPACT-OPERATED ELECTRICITY GENERATOR FOR PROJECTILES 10 Claims, 1 Drawing Fig.

U.S. C1 3l0/8.4, 102/702, 310/8.7

Int. Cl H0lv 7/00 Field of Search 310/8.1-

[56] References Cited UNITED STATES PATENTS 3,356,026 12/1967 Lubig 310/8.4 X 2,703,530 3/1955 McGee 102/702 2,892,411 6/1959 Brown et a1 310/8.7 X 3,196,794 7/1965 Meade 310/8.3 X 3,320,890 5/1967 Ciccone et a1. 310/8.7 X FOREIGN PATENTS 980,380 1/1965 Great Britain 102/702 Primary Examiner-Milton O. Hirshfield Assistant Examiner-B. A. Reynolds Attorney-Waters, Roditi, Schwartz & Nissen ABSTRACT: An electrical current generator for projectiles which is operated by impact. A cap is mounted so as to transfer direct forces to a striker which in turn compresses a substance which responds by generating current. To accommodate indirect or angular forces, the cap is mounted for translatory displacement which by a camlike action is converted into axial displacement of the striker to compress said substance.

IMPACT-OPERATED ELECTRICITY GENERATOR FOR PROJECTILES DETAILED DESCRIPTION This invention relates to impact-operated electricity generators for projectiles.

An object of the present invention is to provide an improved type of electrical current generators for projectiles, impactoperated and of high output even when the angle of incidence ofimpact is large.

In impacts of this kind, the projectile tip undergoes a transverse shift by sliding onto a part called the striker. The tip pushes this striker longitudinally to compress a ferroelectric or piezoelectric substance. When an impact is close to normal or perpendicular, compression is transmitted, in known systems, with neither transverse motion nor sliding.

In many devices and projectiles, the priming power for a service charge is supplied by the above-noted compression of some piezoelectric or ferroelectric substance on impact. Such substance is provided most frequently in the form of a ceramic pellet mounted in the forepart of the projectile, its axis being merged with or parallel to that of the projectile itself.

The main disadvantage of such an arrangement is the poor efficiency resulting when the impact angle of incidence exceeds 60. With such impacts indeed, only a minor portion of the so-called electric saturation charge, which would be given by the same substance if compressed under optimal conditions, is recuperated at the generator terminals.

In order to obtain, nevertheless, a high operational probability for the device supplied with power by such generator, various solutions have been suggested in the past. By making use, for example, of a large-sized ferroelectric pellet, stacked pellets connected in parallel, a hemispherical ceramic capsule or a number of pellets arranged around the periphery of the nose so that at least one of them would stand in the right position on impact, the power available at the generator terminals can suffice to operate an electrical primer even at high angles of incidence. However, the disadvantages common to all these solutions include the large amount of space they occupy, their complexity and the high cost of design and construction. Again, it is possible to use highly sensitive primers, but this runs counter to safety requirements.

The present invention allows high efficiency to be obtained even when the impact angle of incidence is only slightly less than the limit permitted by the geometry of the projectile nose, and thus makes it possible to use a small-dimensioned ceramic pellet in a simple assembly as a current generator capable of starting through a wire or slotted conductor an electric explosive primer even when conditions are unfavorable.

The invention makes effective use of the radial components of the forces of compression which appear on impact, instead of using only their longitudinal component as in the standard assemblies.

In the device according to the invention, the portion of the projectile located in front of the piezoelectric or ferroelectric substance consists essentially of: first a striker whose back face is designed to compress or percuss the front surface of said substance, and whose front face is planar or convex and preferably conical with a large aperture angle; second, a cap which under sufficient radial stress can relay a radial motion, on top of said striker, with a plane or concave part inside intended for pushing the striker and having a shape matching the latter and capable therefore of transmitting to the striker the compressive stresses arriving from the outer portion of such cap.

The operating principle of this device is as follows: on an impact at low angle of incidence, the generator according to this invention operates as do certain generators already known; the forepart ofthe cap is compressed by the target and transmits the force almost axially to the striker which likewise compresses the ferroelectric substance axially; on impact at high incident angle, the cap on the contrary undergoes a radially directed shift'and through sliding of its concave interior, previously described, on the convex front of the striker, communicates to this latter a compression motion or wave almost axial in direction, thus occasioning a compression of the ferroelectric substance under extremely favorable conditions.

The attached figure illustrates, for a better understanding of the invention and without limitation, one embodiment of the invention.

In the drawing, the ferroelectric substance 1 is shown in the form of a ceramic pellet having two silvered surfaces which form terminals. The cap 2 and anvil-piece 3 are connected to plug pins 4.

Striker 5, whose upper convex face in conical in this case, is held at a slight distance from the face of pellet l by an inside bolster 6 which can shear on impact. This arrangement offers the double advantage of avoiding excessive compression of pellet 1 if acceleration factors on discharge of the missile are considerable, and of contributing a distinct improvement in the electrical output of the generator in relation to an assembly wherein the striker would be in direct contact with pellet 1 or 2.

Bracket 6 at the same time assures alignment of the striker movement.

Cap 7 rests on striker 5 and comprises a belt 8 which is shearable on impact at high incidence to allow the translatory radial motion previously described. Cap 7 and striker 5 have cooperating camlike surfaces and 5a which convert transverse displacement of cap 7 into axial displacement of striker 5. A bracket block 9, insulating member 10 and cap 11 of the projectile onto which last the cap 7 is screwed, complete the assembly.

Substance 1 can be ferroelectric, piezoelectric, ferromagnetic or it can have any other properties which allow the direct or indirect generating of an electric current through application of a compressive force. Furthermore, it can be of any other character beside ceramic and can take on any other form beside that of a pellet.

A A device for control of impedance can be incorporated into the electrical circuit in the form, for example of a thin insulating washer interposed between pellet l anvil-plate anvilplate 3 or in any form.

The sliding of the cap on the striker can be facilitated by a lubricant, surface treatment or any other process.

Striker 5 may or may not be separated by a small gap from cap 7 on the one hand, or from pellet 1 on the other.

The invention can be applied to all types of missile in which practically instantaneous operation is required no matter what the degree of incidence, and is particularly useful in cavitycharged missiles.

The invention thus provides a new type of electric generator for projectiles, which on impact delivers the electric power necessary for the operation of one or more electrical devices or other appliances. This generator is particularly suitable for giving high efficiency on impacts at high angle of incidence.

It is characterized by the following points, which an be taken singly or in various combinations of one with the other:

1. The active part of the generator is a substance capable of supplying directly or indirectly electric power when undergoing static or dynamic compression.

This substance is compressed on impact by a part or subassembly called the striker, of which the forepart is of convex or planar shape, a conical shape of large aperture angle being particularly recommended.

This striker itself is surmounted by a device called the cap, comprising in its rear part facing the forepart of the striker a concave or planar face such that a shifting of the cap perpendicularly to the axis of the missile can, through sliding of the two facing surfaces of the striker and cap in relation to each other, cause a movement of the striker in the direction of the projectile axis.

2. On impact at low angle of incidence, the cap transmits the compressive force to the striker without any sliding of these two parts in relation to each other.

3. On impact at a high angle of incidence, the cap can acquire a transverse movement slide on the face of the striker, and produce a longitudinal motion in this latter.

4. The movement of the striker is guided in such a way as to be only longitudinal.

5. The transverse movement of the cap is made possible by the existence of a section showing weak resistance to transverse stresses, a breakdown primer or any other process using or not using an impact break feature.

6. The assembly can comprise or not comprise a slight air gap between the striker and the active substance. If it does, the movement of the striker toward the active substance can be facilitated on impact by shearing or rupture of any part whatsoever of the assembly.

7. The assembly may comprise a slight air gap between striker and cap.

8. A lubricant, surface treatment or any other process may be used to facilitate the sliding of the cap on the striker.

9. Any device for impedance adjustment may be interposed in the electrical circuit between the source of power and the device it has to feed.

What is claimed is:

1. An impact-operated electrical current generator for a projectile comprising impact receiving means, support means supporting the impact receiving means for displacement, upon impact, axially or transversely relative to the projectile, a compression responsive substance adapted to generate electrical current, and striker means cooperating with the impact receiving means upon axial or transverse displacement of the latter to compress said substance to generate said current, said striker means and impact receiving means including mutually cooperating surfaces such that transverse displacement of said impact receiving means is converted into a substantially axial displacement of said striker means.

2. A generator as claimed in claim 1 comprising means to support the striker in spaced relation to said substance prior to impact.

3. A generator as claimed in claim 1, wherein the impact receiving means and striker means having cooperating camlike surfaces to convert transverse displacement of the latter.

4. A generator as claimed in claim 1, wherein said support means is a shearable beltlike member integral with said impact receiving means.

5. A generator as claimed in claim 4, wherein the means to support the striker is a shearable bolster.

6. A generator as claimed in claim 1 further comprising an anvil below said substance, a cap atop said substance, and electrical connections to said anvil and cap.

7 A generator as claimed in claim 1, wherein the impact receiving means and striker means have surfaces which are respwtively concave and convex.

8. A generator as claimed in claim 7, wherein the surfaces are conical.

9. A generator as claimed in claim 1 comprising a bracket block supporting said substance and striker on said projectile.

10. A generator as claimed in claim 1, wherein said impact receiving means is supported on the projectile. 

1. An impact-operated electrical current generator for a projectile comprising impact receiving means, support means supporting the impact receiving means for displacement, upon impact, axially or transversely relative to the projectile, a compression responsive substance adapted to generate electrical current, and striker means cooperating with the impact receiving means upon axial or transverse displacement of the latter to compress said substance to generate said current, said striker means and impact receiving means including mutually cooperating surfaces such that transverse displacement of said impact receiving means is converted into a substantially axial displacement of said striker means.
 2. A generator as claimed in claim 1 comprising means to support the striker in spaced relation to said substance prior to impact.
 3. A generator as claimed in claim 1, wherein the impact receiving means and striker means having cooperating camlike surfaces to convert transverse displacement of the latter.
 4. A generator as claimed in claim 1, wherein said support means is a shearable beltlike member integral with said impact receiving means.
 5. A generator as claimed in claim 4, wherein the means to support the striker is a shearable bolster.
 6. A generator as claimed in claim 1 further comprising an anvil below said substance, a cap atop said substance, and electrical connections to said anvil and cap.
 7. A generator as claimed in claim 1, wherein the impact receiving means and striker means have surfaces which are respectively concave and convex.
 8. A generator as claimed in claim 7, wherein the surfaces are conical.
 9. A generator as claimed in claim 1 comprising a bracket block supporting saiD substance and striker on said projectile.
 10. A generator as claimed in claim 1, wherein said impact receiving means is supported on the projectile. 